Ipsilateral Hemiparesis in a Patient With Existing Contralateral Hemiparesis: A Case Report of a Rare Presentation of Ischemic Stroke.

Supratentorial strokes causing ipsilateral hemiparesis (ILH) are rare. We report a middle-aged male with multiple atherosclerotic risk factors, who had previously suffered a right-hemispheric stroke that caused left hemiplegia. Subsequently, he presented with worsening left-sided hemiplegia, with imaging revealing a left-hemispheric stroke. Diffusion tensor tract imaging showed crossed motor tracts, with disruption of the left-sided pyramidal tract. During his stay, he developed right hemiplegia due to the expansion of the same left-hemispheric infarct. Potential mechanisms for ILH in a stroke include injury to reorganized tracts following an initial insult and congenitally uncrossed motor tracts. In our patient, after his first stroke, the left hemisphere likely assumed greater ipsilateral motor control, causing ILH after the recent stroke. Our case adds to the literature on this interesting phenomenon and provides further insight into post-stroke recovery.